Many people wonder whether wearable devices, from smartwatches to Google Glass, will be all that useful. Evernote CEO Phil Libin isn’t one.

In a recent interview at the note-taking-app company’s Redwood City, Calif., offices, Libin waxed enthusiastic about the potential for wearables, saying that Evernote is working on ways to help people be productive on such devices.

“I think wearables will be vastly transformative,” Libin said, adding that he believes such devices will be more disruptive than smartphones and tablets.

Libin said he also was an early believer in tablets, describing how Evernote staffers used leaked information about the iPad to create cardboard tablets before Apple released the device; they then scotch-taped mock-ups of how Evernote might look to help design their tablet app.

Libin offered no specifics on Evernote’s plans with respect to wearables. But he said such devices will differ from other computing devices for more important reasons than the smaller screen.

Looking to the shift from PCs to mobile devices, Libin said the biggest differences was about “session length” and “context.” People spend 40 minutes on their laptops a few times per day, but two minutes on their phones 100 times per day.

With wearables, a session may last less than two seconds, and there may be 1,000 a day, he believes.

The killer feature of the new devices, he said, will be “eliminating the times you’re not quite sure what’s going on,” calling that “hyperawareness.”

These two factors have big implications for software developers. One is that the idea of “apps” will disappear, Libin said. “When it takes longer to start an app than you would spend in the app, it doesn’t make sense anymore to use them.”

Evernote will keep that in mind, said Libin, as it designs services for wearables. One hint: People won’t take notes on smartwatches, he said, other than voice notes perhaps. On that point, Libin has a recommendation for designers – put the microphone on the underside of people’s wrists. It’s “more Secret Service,” to talk into them that way, he said. “I feel dorkier doing it like this,” as he talked to the top of the Pebble watch that he wears.

Libin also spoke well of “anticipatory computing” tools like Google Now, around which the search company has designed its latest computing platform, Android Wear, that will power smartwatches from LG, Motorola and others.

“Google is the most interesting company doing this” since it is “strong in all of these areas” from devices to the services that will run well on them, said Libin.

Google does have one big challenge, he argued: its reliance on advertising to make money. “I would never accept a pixel of advertising” on my glasses, Libin said. “If you’re only going to use a device for a second, how much of that session length will you waste on advertising?”